hack·le

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To chop roughly; mangle by hacking.
• intransitive verb To hack.
• noun Any of the long, slender, often glossy feathers on the neck of a bird, especially a male fowl.
• noun The erectile hairs along the back of the neck of an animal, especially of a dog.
• noun A feather, usually from the neck of a chicken, used in trimming a fishing fly.
• transitive verb To trim (an artificial fishing fly) with a hackle.
• idiom (get (one's) hackles up) To be extremely insulted or irritated.